U.P. yeast adds new flavors to local beers

From Blackrocks Brewery in Marquette, to Keweenaw Brewing Company in South Range, to Upper Hand Brewing in Escanaba, the Upper Peninsula is home to more than a dozen breweries. A good number distribute into Lower Michigan, Wisconsin and beyond, exporting the inimitable taste of the Northland to drinkers far and wide.

To be fair, not every ingredient in U.P.- (or Michigan-) made beer comes from our neck of the woods. Our breweries might draw their water from local lakes and aquifers, but the grains (malt) and hops that flavor our beer generally come from farther-flung locales: the Dakotas, Alberta, Washington state.

Until recently, the same could be said for the yeast cultures critical to the fermentation process. A handful of big companies--Wyeast and White Labs, among others--supply the majority of homebrewers and many upstart commercial brewers with a dizzying array of culture options. These cultures are the flavor "paints" of the brewing world: Each produces slightly different flavors during the fermentation process, giving brewers plenty of leeway for experimentation.

But these "corporate" cultures are produced to rigorous specifications in sanitized labs. There's no surprise or variety within strains; every packet is exactly the same. And there's no local "signature"--what winemakers call "terroir." The yeast lab could be in Beijing, Berlin,or Baltimore, and the result would be exactly the same.

Local yeast for local beer

Thanks to Craft Cultures, a small "boutique lab" in Hancock, brewers in the U.P. and beyond now have an alternative to non-local yeasts. Owner Emily Geiger is also Keweenaw Brewing Company's resident microbiologist, so she knows a thing or two about brewing yeast.

Geiger spends much of her time collecting and purifying yeast from "wild" locations around the Upper Peninsula; she has isolated three distinct U.P. strains thus far, and has "two more that we aren't finished characterizing yet," she says.

Each local strain is as varied as the U.P.'s rugged landscape: The Eagle River Ale Yeast is ideal for Belgian-style ales, for instance, while the U.P. Lager Yeast is a fit for malty lagers.

Geiger isolates her cultures with "yeast traps," basically cheesecloth-covered Mason jars filled with wort, the unfermented malt mixture that transforms into beer during brewing. She places the traps in carefully chosen outdoor locations and leaves them for a few days, hoping no animals (or hikers) upend them in the meantime.

Once she's collected a sample, Geiger takes it back to her lab in Finlandia University's business incubator. Each sample has a bevy of microorganisms swimming in it; Geiger's job is to use proven microbiological practices to isolate, purify (remove potentially harmful bacteria and fungi) and characterize (basically, assess the biological characteristics of) each useful strain of yeast. This process can take one to three weeks, depending on the nature of the sample.

Once characterization is complete, Geiger brews small experimental batches to reveal the strain's flavor profile. "We don't have a liquor license, so we can't sell those experimental batches," she says, "but they allow us to provide practical guidance to our brewing partners."

Of course, those brewing partners can sell beer brewed with Craft Cultures' yeast strains. Despite doing "virtually no marketing," Craft Cultures has clients all across Michigan: The Library in Houghton, Blackrocks and the Ore Dock in Marquette, Beggar's Brewery in Traverse City, and New Holland Brewing in Holland, to name just a few.

"One of the biggest demands in the brewing industry right now is proprietary yeast," says Geiger. "Brewers want distinctive, local strains that set them apart."

The benefits of locally sourced yeast

One of Geiger's happiest clients is Stormcloud Brewing, an ascendant craft brewery near Traverse City. Stormcloud ordered a batch of Eagle River Ale Yeast for its Harvest Saison, brewed earlier this year with local yeast, grains and hops.

According to Stormcloud cofounder Brian Confer, it's like nothing he's brewed with before--in a good way.

"This strain is unique. It tastes a lot like a Saison yeast, but also has notes of apple and a deeper earthiness than our usual Saison strain," says Confer. "It's pretty complex."

Stormcloud opened in 2013, and Eagle River is the first wild yeast strain to make it into a production beer there. According to Confer, taproom demand for the Harvest Saison has been healthy. The Stormcloud team also shopped the brew at a couple festivals downstate and garnered positive reviews from discerning attendees.

"There's been a good amount of interest for this beer at the brewpub, at the Empire Hops Festival where we debuted it, and at the Detroit Beer Festival--where we called it 'A Yooper and a Troll Kissing in a Tree,'" Confer laughs. "There's high interest for all-Michigan-ingredient beers across the state."

"It's just fun to play with these ingredients, see what the result is, and contemplate that we source everything within easy driving distance--less than a tank of gas, actually," he adds.

Confer is quick to point out he's not the only Michigan brewer wading into the world of wild yeast (and other local beer ingredients). Rockford Brewing Company's Michigan Pale Ale has all-Michigan ingredients too, says Confer, and New Holland Brewing Company has "several...and is gaining a lot of attention for it."

"Steve Berthel, New Holland's head pub owner, has been hugely supportive of our efforts," adds Geiger. "He's very proactive when it comes to reporting issues with our cultures--he's committed to working together to troubleshoot our processes, which is really what science is all about."

Contamination, inconsistency and other challenges

In the fermentation business, troubleshooting is important precisely because so much can go wrong. Although Geiger's proprietary process is highly effective at isolating beneficial yeast from harmful microorganisms, the fundamental challenge of sourcing wild yeast is simply that "you don't know what you're going to get," she says.

It takes a minute quantity of harmful bacteria or yeast to contaminate a yeast sample to the point that it's not safe or desirable to use. And even Geiger can't predict what's going to happen every time she goes out to collect a sample. At the same time, brewers are constantly asking her to push the envelope and source new, different strains--a challenging prospect.

"When we're using something that purposely has never been used before, we don't know what we're getting," she said in a recent interview with Eater magazine.

According to Geiger, "killer yeast"--which tolerates exposure to ethanol at higher concentrations than typically found in beer--is particularly worrisome. Geiger recently encountered a strain of yeast that can survive exposure to a 15% ethanol solution, stronger than most wine. To keep killer yeast out of her clients' brewing systems, she runs an ethanol tolerance test on every sample she collects and discards any that appear too tolerant of the sauce.

Samples' origins also matter. Although some breweries attempt to isolate "hyper-local" strains from their premises, Geiger doesn't recommend setting yeast traps inside, where human-toxic yeasts are more likely to be present. "Trapping yeast outside reduces risk somewhat," she says.

Geiger's practices appear to be paying off. "I trusted Emily to deliver a pure yeast culture, one that didn't contain bacteria that would be potentially difficult to remove from the brewery," says Stormcloud's Confer. "We used our standard cleaning regimen after transfer of the Harvest Saison and I'm happy to report we've had no contamination issues."

That's music to Geiger's ears. "We want to make money, but we're also committed to working with and educating brewers in Michigan and beyond," she says. "Many brewers look at yeast as just another ingredient, and it's our job to teach them that it's a real, living thing."